1. Field of the Invention
The present invention relates to a method for manufacturing a silicon carbide semiconductor device, more particularly, a method for manufacturing a silicon carbide semiconductor device employing a silicon carbide substrate having a hexagonal crystal structure.
2. Description of the Background Art
In recent years, a silicon carbide substrate has begun to be used to manufacture a semiconductor device. Silicon carbide has a band gap larger than that of silicon. Accordingly, a semiconductor device employing such a silicon carbide substrate has high breakdown voltage, low on-resistance, and a property less deteriorated under high temperature environment, advantageously.
In order to improve a yield of a semiconductor device employing the above-described silicon carbide substrate, it is required to control dislocations in the silicon carbide substrate. For example, Japanese Patent Laying-Open No. 2010-184833 discloses that deterioration of property of a device (semiconductor device) and decrease of yield thereof can be suppressed by forming an angle of 22.5° or smaller between the [0001] axis and a direction of dislocation line of threading dislocations that penetrates the (0001) plane.
In the method described in Japanese Patent Laying-Open No. 2010-184833, the density of dislocations is reduced by controlling the direction of the dislocation line in an epitaxial film formed on the silicon carbide substrate. However, with only the reduction of the density of dislocations in the epitaxial film, it is difficult to sufficiently improve the yield of the semiconductor device.